A multiplexer or logic function circuit such as an exclusive OR (XOR), non-exclusive (NXOR), OR, NOR, AND or NAND circuit is usually formed on a semiconductor integrated circuit chip. For example, U.S. Pat. No. 4,963,767 dated Oct. 16, 1990 by Nguyen X. Sinh discloses an ECL (emitter coupled logic) multiplexer of non-differential type. U.S. Pat. No. 4,866,306 dated Sep. 12, 1989 by Daniel F. Hopta discloses an ECL multiplexer, which has series gates with differential outputs and non-differential inputs. U.S. Pat. No. 4,628,216 dated Dec. 9, 1986 by Nikhil C. Mazumder discloses multiplexers and XOR and other logic circuits. Also, ELECTRONICS LETTERS, 29th Mar. 1990, Vol.26, No.7, pp.430-431, shows a high speed XOR and ELECTRONICS LETTERS, 12th Oct. 1989, Vol. 25, No. 21, pp. 1422-1423, discloses a high speed multiplexer.
However, these prior art circuits have disadvantages--low speed, a small noise margin and/or a large power consumption--due to the use of series gates or non-differential type circuits.